Process for producing electrical resistance elements and the like



June 24, 1930. F. EICHENBERGIER PROCESS FOR PRODUCING ELECTRICALRESISTANCE ELEMENTS AND THE LIKE Filed May 5, 1925 Patented June 24,1930 UNITED STATES PATENT oFFicE FERDINAND EICHENBEBGER, OI AARAU,SWITZERLAND, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO GLOBAR CORPORATION, OFNIAGARA FALLS, NEW YORK, A CORPO- RATION OF NEW YORK I'ROCES FORPRODUCING ELECTRICAL RESISTANCE ELEMENTS AND THE LIKE Application filedKay 5,1923, Serial No. 636,957, and in Switzerland Kay 11, 1922.

The present invention relates in general to the production of formed orshaped bodies, for example in the form of bars, and especially such asare adapted for use as electrical resistance elements of the generaltypes and for general purposes described in my copending applications.

In the drawings:

Fig. 1 is a partly sectional view in elevation showing details ofapparatus that may be used in carrying out features of the invention.

' Fig. 2 is a sectional plan in the plane of the line IIII of Fig. 1.

Where it is sought to produce bodies of this character, especiallyelectrical resistance elements formed wholly or partly from relativelyhard and non-plastic material, such as sand mixtures or metals inpowdered form, as described in my co-pending applications, in whichcase, certain binding mediums, such as graphite or the like, may not beused for one reason or another and where the element cannot be readilyformed by pressing it from a nozzle in the form of a plastic mass, greatdilhculties are presented in the production of bodies or elements.

In accordance with the present invention, these difiiculties ofproduction are overcome or avoided in a manner that is just as simple asit is practical.

The present invention may be practiced by providing in comminuted formthe material which serves for the production of the molded or shapedbody or element, this material, such as silicon carbide, eithersubstantially entirely or a mixture thereof, and one or moreingredients, such as a metal in powdered form and other substancescapable of modifying mechanical or electrical characteristics of thefinal product, with a bindin material, such as a dilute solution ofwater-glass or the like, as may be desired or satisfactory for thearticular purpose at hand, being pressed, as y ramming, into a metalpipe or tube 1, or other desired form, the same constituting a moldwhose inner wall is provided with a liner or coating 2 of paper or othercarbonaceous or heat-decomposable material, the metal tube or othermolding form being provided with small through perforations 3 throughoutits entire surface. In pressing the material of which the moldedproduct, indicated at 4, is composed into the mold, the lower endof thetube 1 may rest against a portion of an anvil or table 5, and thisclosing portion of the latter may be the bottom of a recess in the tablewhich receives the lower end portion of the mold and serves to steadythe same,

With the working material pressed into the metal tube 1, or otherdesired form, and inside the paper lining 2 thereof, the metal tube withits contents can thus be readily heated for the purpose of drying thesame or evaporating any moisture thereof; and this heating may becarried to incandescence or a red heat, without danger of the gasesproduced thereby in the molded body causing the latter to be rendereduseless or damaged, as through the formation of fractures or cracks orby inflation, since any of these gases generated can readily pass outthrough the perforations in the wall of the pipe or tubular mold.Likewise, any gases generated in the combustion or decomposition of thepaper lining 2 of the tube which is burned during the process, canreadily pass ofi and the remains of this paper lining may be readilypushed outof or removed from the metal tube, along with the formed anddried element, after the required heating or burning of the formed bodyor element to produce an element of the desired characteristicsincluding mechanical strength.

The constituents used and the proportions thereof and the extent towhich this process of burning the element is carried will depend to amajor extent uponthe desired characteristics of the resistance elementor portion thereof constituting the desired final product.

It should be understood that the invention claimed is not limited to theexact details of production and characteristics herein spe cificallydescribed, for obvious modifications within the scope of the inventionwill be apparent to persons skilled in the art to which thisinventionrelates.

It is claimed and desired to secure by Let-- ters Patent:

1.- The process of producing bar-shaped bodies from hard, non-plasticmaterial, which comprises treating the forming or molding material witha dilute binding material, stamping the mixture into an enclosingmold'provided with through apertures over its entire surface and havingits inner wall lined all over with a relatively thin heatdecomposableenvelope or coating, and burning or incandescing the mold and itscontents to a degree suflicient to solidify said molded material and todecompose said envelope or coating.

4 2. The process of producing formed bodies from relatively hard andnon-plastic material, which comprises pressing said material into anenclosing mold of the desired shape having its wall provided with spacedthrough apertures and its inner surface covered by a lining of paperbetween such surface and the material to be molded, and burning saidmaterial while contained in said mold and its lining to preduce anelement of the required characteristics and to decompose said lining.

v 3. The process of producing formed bodies, which comprises pressingthe material to be molded in an enclosing mold capable of withstandingthe required heating without deterioration and having its wall providedwith through apertures and its inner surface covered by aheat-decomposable liner, and burning said material while contained insaid mold and its liner to a degree sufficient to decompose the linerand produce a body of the required characteristics.

4. The method of producing molded and heat-hardened electricalresistance elements from a substance containing silicon carbide as anessential ingredient, which comprises pressing said substance into anenclosing mold having perforated walls with a heat decomposable spacerbetween said mold and the substance therein, and heating said substancewithin said mold to the extent required to unite the particles of saidsubstance and burn said spacer.

5. The process of producing a self-sustaining'molded resistance elementfrom a substantially non-plastic conducting substance, which comprisespressing said substance into an enclosing mold having perforated wallswith a heat decomposable spacer between said mold and the substancetherein, and heating said substance to the extent required tomechanically unite the particles thereof to form a rigid conductor ofelectricity extending throughout said molded mass.

6. The method of producing an electrical resistance element, whichcomprises pressing a deformable mixture containing silicon carbide as aningredient into a heat-resistant enclosing mold which permits passage ofgases therethrough with a separator readily decomposable by heat betweenthe mold and the molded material, baking said molded materia'l-whileconfined in the. mold at a temperature suificiently hi h to solidify themolded material and ecompose the separator, and removing the moldedelement from the mold. i

7. The process of producing molded electrical resistance heatingelements, which comprises pressing comminuted material 'containingsilicon carbide as an essential and substantial constituent thereof intoan enclosing mold of tubular form and having its wall provided withthrough apertures and with a heat-decomposable liner between said moldand the material "to be molded, heating the mold and its contents to anextent required to solidify said element and to decompose said liner,and removing said element from said mold.

8. The method of producing an electrical resistance element, whichcomprises prepar-

